correct documentation about scan hook (which has never existed)

IkiWiki/UserInfo.pm

@@ -11,7 +11,7 @@ sub userinfo_retrieve () { #{{{
 	my $userinfo=eval{ Storable::lock_retrieve("$config{wikistatedir}/userdb") };
 	return $userinfo;
 } #}}}
-	
+
 sub userinfo_store ($) { #{{{
 	my $userinfo=shift;
 	

doc/plugins/write.mdwn

@@ -32,12 +32,6 @@ hook, a "id" paramter, which should be a unique string for this plugin, and
 a "call" parameter, which is a reference to a function to call for the
 hook.
 
-An optional "scan" parameter, if set to a true value, makes the hook be
-called during the preliminary scan that ikiwiki makes of updated pages,
-before begining to render pages. This parameter should be set to true if
-the hook modifies data in `%links`. Note that doing so will make the hook
-be run twice per page build, so avoid doing it for expensive hooks.
-
 An optional "last" parameter, if set to a true value, makes the hook run
 after all other hooks of its type. Useful if the hook depends on some other
 hook being run first.
@@ -76,14 +70,6 @@ Runs on the raw source of a page, before anything else touches it, and can
 make arbitrary changes. The function is passed named parameters `page` and
 `content` and should return the filtered content.
 
-### scan
-
-	hook(type => "scan", id => "foo", call => \&scan);
-
-This is identical to a preprocess hook (see below), except that it is
-called in the initial pass that scans pages for data that will be used in
-later passes. Scan hooks are the only hook that should modify `%links`.
-
 ### preprocess
 
 Adding a [[PreProcessorDirective]] is probably the most common use of a
@@ -104,6 +90,12 @@ parameters included in the directive are included as named parameters as
 well. Whatever the function returns goes onto the page in place of the
 directive.
 
+An optional "scan" parameter, if set to a true value, makes the hook be
+called during the preliminary scan that ikiwiki makes of updated pages,
+before begining to render pages. This parameter should be set to true if
+the hook modifies data in `%links`. Note that doing so will make the hook
+be run twice per page build, so avoid doing it for expensive hooks.
+
 Note that if the [[htmlscrubber]] is enabled, html in
 [[PreProcessorDirective]] output is sanitised, which may limit what your
 plugin can do. Also, the rest of the page content is not in html format at